Thyroglobulin levels in the sera of thyroid cancer patients are routinely quantified using various agency-approved (e.g. FDA) immunoassays. Physicians frequently order these diagnostic immunoassays to determine thyroglobulin levels in their patients. Therefore it is not surprising that many different companies have developed their own diagnostic tests for purchase and use in the clinical laboratory. Despite the current availability of these numerous thyroglobulin immunoassays, each suffers from inherent limitations. In fact, it is not possible to accurately compare the results obtained from one thyroglobulin immunoassay with those obtained by another. There are two major problems which need to be solved. First, the lack of a universally consistent thyroglobulin standard contributes significantly to variability between FDA-approved immunoassays made by different suppliers. Presently, the only source of human thyroglobulin for use as a standard in immunoassays comes from cadavers or surgically removed human thyroid tissue. The heterogeneity of different lots of human-derived thyroglobulin is a limitation which has not been solved. Second, anti-thyroglobulin autoantibodies present in some thyroid cancer patients'sera can interfere with immunoassays that attempt to detect and quantify thyroglobulin. Currently, there are no clear solutions to either of these dilemmas. In this Phase I SBIR, we propose to solve two of the most significant problems plaguing FDA-approved thyroglobulin immunoassays by expressing human thyroglobulin in transgenic soybean seeds for use as a class II medical device analyte. Taking advantage of this novel platform for expressing thyroglobulin should allow us to produce a highly homogenous standard for immunoassays. Furthermore, the unique advantages of transgenic soybean-derived proteins (e.g. homogeneity, ease of purification, very low cost, elimination of human pathogen transmission, renewable "green technology", etc.) will allow, for the first time, a practical solution for the elimination of anti-thyroglobulin autoantibodies that can interfere with immunoassays. These accomplishments should significantly enhance present day thyroglobulin immunoassays designed to diagnose and monitor patients with thyroid cancers. PUBLIC HEALTH RELEVANCE: In this Phase I SBIR, we propose to solve two of the most significant problems plaguing FDA-approved thyroglobulin immunoassays by expressing human thyroglobulin in transgenic soybean seeds for use as a class II medical device analyte. Taking advantage of this novel platform for expressing thyroglobulin should allow us to produce a highly homogenous standard for immunoassays. Furthermore, this will allow a practical solution for the elimination of anti-thyroglobulin autoantibodies that can interfere with immunoassays. These accomplishments should significantly enhance present day thyroglobulin immunoassays designed to diagnose and monitor patients with thyroid cancers.